Portion of a refrigerator



FIG. 1 is a front perspective view of a portion of a refrigerator showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a top view thereof; and

FIG. 5 is a bottom view thereof.

The broken lines shown in the drawing disclosure are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a portion of a refrigerator, as shown and described. 